While working with strings, their prefixes and suffix play an important role in making any decision. Let’s discuss certain ways in which this task can be performed.
Example:
String = "GfG is best" Input_lis = ['best', 'GfG', 'good'] Output: True Explanation: 'GfG is best' is present in the list. String = "GfG is best" Input_lis = ['Good', 'Bad', 'Nice'] Output: False Explanation: 'GfG is best' is not present in the list.
Check if a string starts with any element in a list using string startswith()
This task can be handled solely by using string startswith() supplying a prefix checklist as an argument to a method as well.
Python3
# initializing stringtest_string = "GfG is best"# initializing prefix listpref_list = ['best', 'GfG', 'good']# printing original stringprint("The original string : " + str(test_string))# using startswith()# Prefix tests in Stringsres = test_string.startswith(tuple(pref_list))# print resultprint("Does string start with any prefix list sublist ? : " + str(res)) |
Output
The original string : GfG is best Does string start with any prefix list sublist ? : True
Check if a string starts with any element in a list using filter()
The filter() method is used to check for each word and startswith() method tests for the prefixing logic at the target list.
Python3
# initializing stringtest_string = "GfG is best"# initializing prefix listpref_list = ['best', 'GfG', 'good']pref_list1 = ['GeeksforLazyroar']# printing original stringprint("The original string : " + str(test_string))# test True caseres = list(filter(test_string.startswith, pref_list)) != []# print resultprint("Does string start with any prefix list sublist ? : " + str(res))# test False caseres = list(filter(test_string.startswith, pref_list1)) != []print("Does string start with any prefix list sublist ? : " + str(res)) |
Output
The original string : GfG is best Does string start with any prefix list sublist ? : True Does string start with any prefix list sublist ? : False
Check if a string starts with any element in a list using in operator
In this example, we are using a Python loop to check if the existing string words are contained in a list or not. Here, we first assigned res to false, if the condition gets satisfied then the result becomes True.
Python3
# initializing stringtest_string = "GfG is best"# initializing prefix listpref_list = ["cat", "dog"]# printing original stringprint("The original string : " + str(test_string))res=Falsex=test_string.split()if(x[0] in pref_list): res=True# print resultprint("Does string start with any prefix list sublist ? : " + str(res)) |
Output
The original string : GfG is best Does string start with any prefix list sublist ? : False
Time complexity: O(n), where n is the length of the prefix list.
Auxiliary space: O(1) as we are not using any additional data structures.
Using find() method
Python3
# Python3 code to demonstrate# Prefix tests in Strings# initializing stringtest_string = "GfG is best"# initializing prefix listpref_list = ['best', 'GfG', 'good']# printing original stringprint("The original string : " + str(test_string))res=Falsefor i in pref_list: if(test_string.find(i)==0): res=True# print resultprint("Does string start with any prefix list sublist ? : " + str(res)) |
Output
The original string : GfG is best Does string start with any prefix list sublist ? : True
Time complexity: O(n)
Auxiliary space: O(1)
Using operator.countOf() method
Python3
# Python3 code to demonstrate# Prefix tests in Stringsimport operator as op# initializing stringtest_string = "GfG is best"# initializing prefix listpref_list = ['best', 'GfG', 'good']# printing original stringprint("The original string : " + str(test_string))res = Falsefor i in pref_list: if(op.countOf(test_string, i) == 0): res = True# print resultprint("Does string start with any prefix list sublist ? : " + str(res)) |
Output
The original string : GfG is best Does string start with any prefix list sublist ? : True
Time Complexity: O(n)
Auxiliary Space: O(1)
Using regular expressions
Python3
import re# initializing stringtest_string = "GfG is best"# initializing prefixpref = 'best'# printing original stringprint("The original string : " + str(test_string))# using regular expressionsres = re.match("^" + pref, test_string)# print resultprint("Does string start with prefix ? : " + str(bool(res)))#This code is contributed by Vinay Pinjala. |
Output
The original string : GfG is best Does string start with prefix ? : False
Time Complexity: O(n)
Auxiliary Space: O(1)
